Engine missing above 3000 rpms

[buckeye_paul]

Challenger 1800 -- 210 Motor
Had the boat in Lake Erie over the weekend of the 4th. All was good Friday and the first time out Saturday. Ran her pretty hard, jumped waves and did numerous spin outs. The second time out that day, we had been out about 30 minutes. My daughter was tubing and I suddenly lost power. The motor was missing above 3000 rpms. I keep a new set of plugs on the boat and changed them on the water. Still had the problem. We limped back to the marina. I went out again that Sunday to be sure it wasn't a temperature issue. It acted the same on a cold motor.

Compression looks good. Port Side Top 124, Middle 128, Bottom 130. Starboard Top 125, Middle 130, Bottom 130.
I seem to have good spark on all six cylinders (below and above 3000 rpms). I checked with an inline spark tester.

I am leaning toward a problem with the stator but wanted to see if anyone else had had this issue before I start changing parts. I checked the stator and here are the results:

Red to black 32.8 Ohms
Red/White to black 33.7 Ohms
Red to Blue 2381 Ohms
Red/White to Blue/White 2166 Ohms
Blue to black 2347 Ohms
Blue/White to black 2131 Ohms


All of these values are low according to the manual, however I don't know if this is the original OEM part or if it has been replaced. I found a website for CDI electronics and their stators have lower values. My stator is lower than both.

I wanted to check the coil packs but this motor is not maintenance friendly in this boat. I would have to pull the motor out to get at them. I wonder if anyone has ever cut access holes the back of this type of boat? I see why some shops don't want to work on them.

Thanks for the help in advance.

 

[Dr Honda]

I don't know if the 210 has a throttle guardian or not. But when they go bad... that's what starts to happen. (cuts on the ignition)

As far as seeing the spark at speed.... not going to happen. Your eye can't resolve 3000 fire's a minute. (that's 50 per second)


On the 210... there is a low speed charging coil, and a high speed charging coil in the stator. It switches over at 2500 rpm. It could be a bad switch box... but more times than not... it's the stator coils. (I'll have to check the manual for the values)

 

[Dr Honda]

I just looked up the values you posted... and all of them are low.

It should be 90~140 ohms on the red-red/white to black.

and

3500~4200 ohms from the blue to red and blue/white to red/white.

 

[buckeye_paul]

I don't think there is a Throttle Guardian. Where would it be located?
It turns out that I do have an aftermarket stator. I contacted the manufacturer. They said normal resistance on the high speed coils should be 27 to 55 ohms. He said the stator is most likely not the problem. I have voltage tested all components and haven't found the problem. I'm getting power to all of the ignition coils. I'm going to pick up a different spark tester. The in line style that I'm using isn't helping me at all.
I've replaced the fuel filter and made sure the screen on the fuel pick up was clear. Additionally, I put new gas in one of my outboard tanks and ran the motor from it. Problem still exists.
I've noticed that when I run it on the hose it is much better than in the water but still hesitating above 2700 rpms or so.
What am I missing?

 

[GAlivin]

Never had this problem...but was reading about your problem and came across this information:

Manual states: TKS ECM provides engine over-rev protection by progressively cutting off spark to ignition coils.

NOTE: There is no troubleshooting for the TKS ECM. The engine will run without the TKS
ECM. If the TKS ECM is suspect, disconnect and run the engine to systematically troubleshoot

You should probably do this when warm because the TKS ECM electrically controls the enrichment valve to provide a rich fuel charge for starting a
cold engine.

Hope this helps!

 

[buckeye_paul]

Thanks but I already tried that. The motor misses when it is cold or warmed up. No problem starting.

 

[buckeye_paul]

I bought a different spark tester and it was much easier to see that I did have spark on all six cylinders.

So I decided to retest the stator voltages with the DVA because I didn't write anything down before. The results are:

Wire color_______1500 rpms_____ 2000 rpms_____3000 rpms.

Blue_______________264V__________270V___________270V
Blue/W.____________240V_________240V____________246V
Red________________138V_________186V_____________254V
Red/W._____________110V_________144V____________185V

1500 rpms. is idle speed running on the hose. I don't want to go any higher than 3000 rpms out of the water.

There is a big difference in voltage between the red and red/white wires. The red wire at startup begins around 138 volts then climbs to as much as 160 volts without increasing the throttle.

I swapped the wires to the switch boxes and the values remained nearly the same. I disconnected the rectifier / voltage regulator with the same results.

Is it safe to assume there is something wrong with the stator? I have ordered a flywheel puller and expect it later this week. Maybe a visual inspection will provide some answers.

 

[buckeye_paul]

Replaced the stator today with OEM part. It seems to miss now above 2000 rpms. Am I missing something obvious?

Could this be a fuel pump or carb problem?

 

[Dr Honda]

Sorry I've been MIA on this one.


Ummmmmmm............. It's never obvious.


OK, Its obviously not the stator.

I wonder if your neutral safety switch has gone bad? If it's sending info to the ECU or guardian... and it's bad... it will think you are still in neutral, and won't rev up. After that... you will have to get a couple switch boxes.

 

[buckeye_paul]

Sorry I've been MIA on this one.


Ummmmmmm............. It's never obvious.


OK, Its obviously not the stator.

I wonder if your neutral safety switch has gone bad? If it's sending info to the ECU or guardian... and it's bad... it will think you are still in neutral, and won't rev up. After that... you will have to get a couple switch boxes.

Hmmm.... It's not that it won't rev up. I disconnected the ECU as described in the manual but the problem is still there. I haven't found a throttle guardian. It is missing noticeably while running on the hose.

 

[Dr Honda]

Have you replaced the spark plugs? (just checking the basics)

OK... there is a black yellow wire going from the helm, and down to the engine. It's the "Kill" wire. If it's grounded, the engine shuts down. BUT... it's also the wire that would control a rev limiter. So... try this... Disconnect that wire from the ECU, and both switch boxes. That will remove (without a doubt) that it's a simple wiring/lanyard/limiter issue.


BUT... do this with a helper. You may need to reconnect it quickly to get the engine to shut down.

 

[Murph_13]

Maybe this is obvious and you've already addressed/verified this, but are the spark plug wires bad?

Just a thought since it seems like you've verified that everything else seems to be in good working order.

When I replaced spark plugs in my boat the first time I noticed the wires were original and somewhat hard formed...concerned about the age and condition of the wires after handling them I replaced the spark plug wires (Magnecor KV85 wire set...Magnecor wires are one of the best out there IMO, pure silicone jackets, the last set of wires you'll buy...fyi - Magnecor P/N 65218 for the 210HP carb'd engine)...

 

[buckeye_paul]

Have you replaced the spark plugs? (just checking the basics)

OK... there is a black yellow wire going from the helm, and down to the engine. It's the "Kill" wire. If it's grounded, the engine shuts down. BUT... it's also the wire that would control a rev limiter. So... try this... Disconnect that wire from the ECU, and both switch boxes. That will remove (without a doubt) that it's a simple wiring/lanyard/limiter issue.


BUT... do this with a helper. You may need to reconnect it quickly to get the engine to shut down.

OK , disconnected it at the switch boxes, no change. This wire goes directly to the helm. Traced a white/black wire from the ECU to the switch boxes. Found a reference to this wire on a mercury site. It is the rev limiter. Disconnected it from the boxes. No change. I've ordered some new plug wires. I'll see where that gets me.

 

[buckeye_paul]

Maybe this is obvious and you've already addressed/verified this, but are the spark plug wires bad?

Just a thought since it seems like you've verified that everything else seems to be in good working order.

When I replaced spark plugs in my boat the first time I noticed the wires were original and somewhat hard formed...concerned about the age and condition of the wires after handling them I replaced the spark plug wires (Magnecor KV85 wire set...Magnecor wires are one of the best out there IMO, pure silicone jackets, the last set of wires you'll buy...fyi - Magnecor P/N 65218 for the 210HP carb'd engine)...

Early in the process I was going to order new plug wires then got stuck on the stator. Thanks for the advice I ordered a set today but may not have them for a week. I read on a different forum that it's easier to detect arcing around the wires and coils if you do it at night. Unfortunately I work nights a leave before it gets dark and we have plans this weekend. Hopefully the new wires will do the trick. I've been out of the water for almost a month. Thanks

 

[Murph_13]

I hope the new wire set does it for you...and yes, definitely easier at night to check for arcing...might be able to drape something over you while looking in the engine compartment to create the darkness and check? Maybe then you could confirm that the wires need replacing?

Again, hope it's as simple as a new wire set and good luck with it...I'm sure you're becoming a bit frustrated with it...

 

[Murph_13]

buckeye_paul,

Hope you've had a chance to and have resolved your issue, and if so, what did it end up being?

 

[buckeye_paul]

Replaced the stator today with OEM part. It seems to miss now above 2000 rpms. Am I missing something obvious?

Could this be a fuel pump or carb problem?

Update...
It was such a cool summer that I just wasn't very motivated to get the boat running. I finally got back to it.
So after replacing the plugs, fuel filter, plug wires, and stator, there was still no noticeable improvement.

I got a fuel pump rebuild kit and gasket kits for the carbs. I also replaced the fuel hoses after the filter. I gave the carbs a good cleaning and got everything back in place this afternoon. It sounds much better now. No hesitating at or above 2K rpm's. I'm going to try to give it a run in the water before I winterize. Hopefully I get a warm day.

This was a good learning experience.

 

[buckeye_paul]

Somewhat chilly out today but we took her out and I'm happy to report she runs beautifully.